CN113241527A

CN113241527A - FSS unit and double-frequency point independently adjustable FSS

Info

Publication number: CN113241527A
Application number: CN202110447624.8A
Authority: CN
Inventors: 马祎浩; 王大伟; 赵文生
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2021-04-25
Filing date: 2021-04-25
Publication date: 2021-08-10
Anticipated expiration: 2041-04-25
Also published as: CN113241527B

Abstract

The invention discloses an FSS unit and a double-frequency point which are independently adjustable, wherein the FSS unit comprises a square plate, a cross-shaped cross structure at the central position and four peripheral tuning fork structures uniformly distributed on the periphery along the circumferential direction are constructed on the square plate, and each peripheral tuning fork corresponds to one routing wire of the cross-shaped cross structure; the single peripheral tuning fork structure is composed of a U-shaped structure and a T-shaped structure from inside to outside, the tail end of the wiring of the cross-shaped structure is over against the inner arc of the U-shaped structure, and the plate part between the U-shaped structure and the cross-shaped structure is hollowed out by taking the line width of the cross-shaped structure as a reference; the outer wall opposite to the inner arc of the U-shaped structure is connected with the center line end of the T-shaped structure, the center line of the T-shaped structure is directly connected with the wiring of the cross-shaped cross structure, and the wiring of the cross-shaped cross structure is perpendicular to the edge of the square plate. The invention has good angle stability, Q value and transmission coefficient, and ensures accurate selectivity to signals near the resonant frequency point.

Description

FSS unit and double-frequency point independently adjustable FSS

Technical Field

The invention belongs to the technical field of wireless communication receiving, and particularly relates to an active device-based dual-band-pass type spatial Frequency Selective Surface (FSS) structure with independently adjustable resonance points.

Background

Since maxwell predicts the existence of electromagnetic waves by formula, the importance of the electromagnetic spectrum, a limited resource, is gradually increasing in human life. Due to the limitation of the electromagnetic wave frequency spectrum and the mutual superposition of the electromagnetic waves worn in different frequency bands in the space, a series of engineering requirements for shielding, selecting, receiving and the like of the electromagnetic waves with different frequencies are generated in the process of transmitting signals by using the electromagnetic waves. FSS is just one important approach to address these engineering needs. Since the past, FSS has been widely used in the technical fields of stealth technology, radomes, antenna main surfaces, cassegrain antenna sub-reflecting surfaces, and the like.

With the rapid development of wireless communication, in order to meet diversified demands, the electromagnetic spectrum in the space becomes more complex, which also puts higher demands on the FSS frequency selection function. In recent years, the appearance of a Tunable Frequency Selective Surface (TFSS) with Tunable resonance Frequency provides a basis for multiband wireless communication and integration thereof. TFSS is largely divided into three categories: magnetic control TFSS (magnetic Tunable Frequency Selective surface), electric control TFSS (electronic Tunable Frequency Selective surface), mechanical control TFSS (mechanical Tunable Frequency Selective surface).

The electric control TFSS mainly adopts active devices such as a variable capacitance diode and the like to adjust parameters of a circuit equivalent model, so that the effect of adjusting a resonant frequency point is achieved. Electrically controlled TFSS has a better response rate than the other two TFSS. However, few designs have been proposed for individually adjusting two or more pass band resonant frequency points in the currently proposed electrically controlled TFSS.

Aiming at the engineering requirements, the invention provides an active device-based dual-band pass-through type FSS structure with independently adjustable resonance points, and the integration degree and the solution efficiency of the FSS on the response of electromagnetic waves with different frequencies to the engineering requirements are greatly improved through the independent adjustment of the dual frequency points.

Disclosure of Invention

The invention aims to provide a double-frequency band-pass type FSS structure with high Q value, low energy loss and high angle stability, wherein the double-frequency band-pass type FSS structure is independently adjustable in resonance point.

In order to achieve the purpose, the invention is realized according to the following technical scheme:

an FSS unit comprises a square plate, wherein a cross-shaped cross structure at the central position and four peripheral tuning fork-shaped structures uniformly distributed on the periphery along the circumferential direction are constructed on the square plate, and each peripheral tuning fork corresponds to one routing wire of the cross-shaped cross structure; the single peripheral tuning fork structure is composed of a U-shaped structure and a T-shaped structure from inside to outside, the tail end of the wiring of the cross-shaped structure is over against the inner arc of the U-shaped structure, and the plate part between the U-shaped structure and the cross-shaped structure is hollowed out by taking the line width of the cross-shaped structure as a reference; the outer wall opposite to the inner arc of the U-shaped structure is connected with the center line end of the T-shaped structure, the center line of the T-shaped structure is directly connected with the wiring of the cross-shaped cross structure, and the wiring of the cross-shaped cross structure is perpendicular to the edge of the square plate.

Preferably, a rectangular hollow-out part is formed in the middle of each of the four edges of the square plate.

Preferably, the short side of the rectangular hollow part is led out with a wiring with the same line width as the short side, and the wiring is connected with wirings led out from the short sides of other rectangular hollow parts to form an equipotential region.

Preferably, the four wiring ends of the crisscross cross structure are arc-shaped.

Preferably, a variable capacitance diode is arranged between the tail end of the wiring of the cross-shaped cross structure and the inner arc of the U-shaped structure.

Preferably, the square plate has a dielectric constant of 2.2 and a loss tangent angle of 0.0009.

The invention also discloses a double-frequency point independently adjustable FSS, which is composed of the FSS units with two different resonance frequency points, wherein the FSS units adopt the same type arrangement mode of oblique angles.

Compared with the prior art, the invention has the following characteristics:

compared with the conventional FSS structure, the FSS structure realizes the function of band-pass type double-frequency point adjustment, and is beneficial to further integration of wireless communication equipment; the high-precision phase-locked loop has good angle stability, Q value and transmission coefficient, and ensures accurate selectivity of signals near a resonant frequency point.

Drawings

FIG. 1 is a diagram illustrating the structure and parameters of the basic unit of the structure of the present invention;

FIG. 2 is a schematic diagram showing the arrangement of the basic units of the structure of the present invention;

FIG. 3 is a graph showing the transmittance of the present invention under different capacitance conditions;

fig. 4 is a graph of the frequency response of the present invention occurring at different angles of incidence.

Detailed Description

The present invention will be described in further detail below with reference to specific embodiments thereof.

As shown in fig. 1, this embodiment relates to an FSS cell, and the basic FSS cell of this embodiment is constructed on a 12mm by 1mm rogues RT/gravity 5880 square plate, which has a dielectric constant of 2.2 and a loss tangent angle of 0.0009.

The FSS unit comprises a cross-shaped cross structure 1 at the center and four peripheral tuning fork-shaped structures 2 uniformly distributed on the periphery along the circumferential direction, and four wiring tail ends 1-1 of the cross-shaped cross structure are in arc shapes corresponding to the line widths of the four wiring tail ends.

Each peripheral tuning fork corresponds to one routing wire of the cross-shaped cross structure. The single peripheral tuning fork structure is composed of a U-shaped structure 2-1 and a T-shaped structure 2-2 from inside to outside, the tail end 1-1 of the wiring of the cross-shaped structure is over against the inner arc of the U-shaped structure 2-1, and a substrate part 3 between the U-shaped structure and the cross-shaped structure is hollowed out by taking the line width of the cross-shaped structure as a reference. The outer wall opposite to the inner arc of the U-shaped structure is connected with a center line end 2-2-1 of the T-shaped structure, and the center line of the T-shaped structure and the routing of the cross-shaped crossed structure are in the same straight connection. The straight line of the cross-shaped cross structure is perpendicular to the edge of the square plate.

The resonance point is deviated by adopting the variable capacitance diode, and the variable capacitance diode is arranged between the tail end of the wiring of the cross structure and the inner layer of the U-shaped structure 3.

The middle parts of the four sides of the basic FSS unit form a cuboid hollow 4 respectively, and the cuboid hollow structure is used for isolation. The isolation between adjacent FSS units can be realized by punching, etching the substrate and the like. The inner wall of the hollow cuboid structure is plated with metal to form a reference ground.

As shown in fig. 2, the dual-frequency-point individually tunable FSS based on an active device in this embodiment is composed of two FSS units operating at different resonant frequency points, and for convenience of description, a basic FSS unit having a resonant frequency point in the L-band is referred to as a first-type unit a, and a basic FSS unit having a resonant frequency point in the S-band is referred to as a second-type unit B.

Basic FSS units are arranged in the same type with diagonal angles, and FSS units of different types are uniformly distributed on the FSS structure, so that the FSS structure has good central symmetry.

In the rectangular isolation structure with the hollowed FSS unit, the wiring with the line width consistent with the length of the short side is led out from the short side of the rectangular isolation structure and is connected with the lines led out from the short sides of other rectangular isolation structures to form an equipotential area. As shown in FIG. 1, the invention is a parameter labeling diagram of a basic unit of the structure, four sides around the basic unit are provided with rectangular notches with length of d/2 and moderate width, and conductor metal is plated in the notches. The wiring is led out from the narrow side of the rectangular gap to form an equipotential area for providing potential difference. The internal wiring structure of the basic unit consists of a cross-shaped cross structure wiring at the center, a U-shaped structure at the periphery and a T-shaped structure. The above structure can be obtained by rotating the structure in one direction for 3 times by 90 degrees each time by taking the center as an axis, so the detailed structural description is given by selecting the upper half part in the vertical direction in the figure: in the parameter notation of fig. 1, d represents the side length of the basic unit, b represents the width of the protruding part of the U-shaped structure relative to the central axis, a represents the length of the U-shaped structure in the vertical direction, s represents the distance between the cross structure and the parallel side inside the U-shaped structure, w represents the line width used for wiring the structure, and c represents the distance between the upper side of the U-shaped structure in the unit and the wiring led out by the corresponding transition structure. The values of the parameters were obtained by optimization, as shown in table 1:

TABLE 1

As shown in fig. 2, which is a schematic diagram of the arrangement of the basic units of the structure of the present invention, the adjacent sides of the first type of basic units and the second type of basic units contact with each other by using the isolation structure as a transition, and the basic units of the same type are arranged according to the diagonal. The actual FSS structure is in units of the structure shown in fig. 2, with periodic rollovers going outward.

Fig. 3 is a graph showing the transmission coefficient performance of the present invention under different capacitance conditions, which is simulated by ANSYS software. In the figure, C1 represents the capacitance of the varactor mounted on the first type basic cell, C2 represents the capacitance of the varactor mounted on the second type basic cell, and when C1 or C2 are changed alone, the other resonance point shows good stability. Specific values of C1 and C2 are shown in table 2:

TABLE 2

C1	C2
		0.30pF	1.8pF
0.42pF	2.0pF
		0.54pF	2.2Pf
0.66pF	2.4pF

Fig. 4 shows a frequency response diagram of the structure of the present invention caused by different incident angles under the conditions of C1-0.45 pF and C2-1.8 pF. It can be seen that the frequency response of the FSS structure is almost free of shift at different angles of incidence, showing a very strong angular stability.

The active device is adopted to cause deviation to resonant frequency points, adjacent FSS units are in transition contact by taking a rectangular isolation structure, and FSS units of the same type are arranged diagonally. The invention can independently adjust the resonance frequency point of the FSS structure in a certain range, and has good angle stability and transmission coefficient performance.

The invention has been described above with reference to the accompanying drawings, it is obvious that the invention is not limited to the specific implementation in the above-described manner, and it is within the scope of the invention to apply the inventive concept and solution to other applications without substantial modification, or with substantial modification.

Claims

1. An FSS unit is characterized by comprising a square plate, wherein a cross-shaped cross structure at the central position and four peripheral tuning fork-shaped structures uniformly distributed around the square plate along the circumferential direction are constructed on the square plate, and each peripheral tuning fork corresponds to one routing wire of the cross-shaped cross structure; the single peripheral tuning fork structure is composed of a U-shaped structure and a T-shaped structure from inside to outside, the tail end of the wiring of the cross-shaped structure is over against the inner arc of the U-shaped structure, and the plate part between the U-shaped structure and the cross-shaped structure is hollowed out by taking the line width of the cross-shaped structure as a reference; the outer wall opposite to the inner arc of the U-shaped structure is connected with the center line end of the T-shaped structure, the center line of the T-shaped structure is directly connected with the wiring of the cross-shaped cross structure, and the wiring of the cross-shaped cross structure is perpendicular to the edge of the square plate.

2. The FSS cell of claim 1, wherein a rectangular hollow is formed in the middle of each of the four sides of the square plate.

3. The FSS cell of claim 2, wherein a short side of said rectangular hollow-out portion leads out a wiring having a width corresponding to the length of the short side, said wiring being connected to wirings led out from short sides of other rectangular hollow-out portions to form an equipotential region.

4. The FSS cell of claim 1, wherein the four trace ends of the criss-cross structure are arcuate.

5. The FSS cell of any of claims 1 to 4, wherein a varactor is provided between the end of the crisscross trace and the inner arc of the U-shaped structure.

6. The FSS cell of any of claims 1-4, wherein said square plate material has a dielectric constant of 2.2 and a loss tangent angle of 0.0009.

7. A dual frequency point individually tunable FSS, characterized by being composed of FSS units according to any of claims 1-6 at two different resonance frequency points, said FSS units being arranged in a diagonal and homotypic manner.